import com.sun.javafx.css.parser.DeriveSizeConverter;

class Base{
    public Base(){
        System.out.println("Base()");
    }
}

class Derived extends Base{
    public Derived(){
        //super() 注意子类构造方法中会默认调用父类的无参构造方法super()
        //用户没有写时，编译器会自动添加，而且在子类构造方法中的第一条语句
        //并且只能出现一次
        System.out.println("Derived()");
    }
}

public class test3 {
    public static void main(String[] args) {
        Derived derived = new Derived();
    }
}
